1. Field of the invention
The present invention relates to a filter for reducing evaporative fuel emissions from an internal combustion engine. More particularly, the present invention relates to a filter for placement on an engine, downstream of a throttle plate, to adsorb evaporative emissions after the engine has been turned off.
2. Description of the Background Art
The great majority of internal combustion engines in use today are fuel-injected engines. When a fuel-injected engine is switched off after use, a small amount of residual fuel volatilizes and escapes from the injector tips. While a vehicle is sitting over time after use, this evaporated fuel may pass outwardly through the intake manifold, the intake air ducts and air filter, and may escape into the atmosphere, thus contributing to air pollution. It would be desirable to minimize this type of inadvertent evaporative emissions leakage.
Many different types of filters are known for use in filtering evaporative fuel emissions in specific applications. Examples of some of the known filter types are described in U.S. Pat. Nos. 4,133,762, 5,429,099, 5,453,118, and 5,912,368.
The assignee of the present invention has developed a new type of xe2x80x98wickingxe2x80x99 fiber material that has been used for some filter applications. This material includes hollow spaces within the individual fibers, and this hollow space may be used to house a reactive or adsorbent material. Some issued patents relating to this wicking fiber, and to filters containing this type of fiber include U.S. Pat. Nos. 5,057,368, 5,704,966, 5,713,971, 5,744,236, 5,759,394, 5,891,221, 5,902,384, 5,951,744, 6,004,381, 6,048,614, 6,117,802, and 6,127,036. Other patents using this fiber technology are pending.
Although the known devices have utility for their intended purposes, a need still exists in the art for an improved evaporative emissions filter, adapted to adsorb fuel vapors within an intake system of an internal combustion engine, subsequent to the engine being turned off. Preferably, such a filter would be capable of regeneration, so as to be repeatably usable over many cycles of engine operation.
The present invention provides a filter for use in removing residual fuel vapors from within an engine""s intake system, downstream of a throttle body, after the engine has been turned off.
A filter in accordance with the present invention, generally, includes:
a filter element for placement within an intake air flow passage, the filter element comprising a plurality of fibers;
each of the fibers having an outer surface;
each of the fibers further having a longitudinally extending internal cavity formed therein, and having a longitudinally extending slot formed therein extending from the internal cavity to the outer fiber surface; and
wherein the filter further comprises a hydrocarbon-adsorbing material disposed within the internal cavities of the fibers.
The hydrocarbon-adsorbing material may be a solid material such as, e.g., carbon, or may be a liquid such as a relatively non-volatile organic solvent. Suitable organic solvents, which may be used in the fiber cavities, include mineral oils and paraffin oils.
In one embodiment of the invention, each of the elongated fibers includes a central stem and a plurality of lobes extending outwardly from the central stem, with each lobe having a longitudinally extending internal cavity on each side thereof, whereby a longitudinally extending slot is defined between adjacent lobes.
It is preferred that the filter be constructed and arranged to minimize pressure drop therepast, limiting the pressure drop to less than 5 inches of mercury at a flow rate of 5,000 cubic feet per minute (CFM) of air flow therepast.
Accordingly, it is an object of the present invention to provide a filter element for placement in an intake flow passage of an engine, the filter element being adapted to adsorb fuel vapors from ambient air in the immediate surrounding area.
It is a further object of the present invention to provide a method and apparatus for removing residual fuel vapors from an engine""s intake system, downstream of the throttle body, after the engine has been turned off.
It is yet a further object of the invention to provide a filter for adsorbing fuel vapors out of ambient air, in which the filter minimizes pressure drop therepast, so as not to interfere with the free flow of air to the engine.
For a more complete understanding of the present invention, the reader is referred to the following detailed description section, which should be read in conjunction with the accompanying drawings. Throughout the following detailed description and in the drawings, like numbers refer to like parts.